There is a multitude of options to safe water, ranging from valves for autoclaves to how water supplies for animals function.
Although it might appears simple, there are very technical aspects to be discussed too.
This is what makes most take a step back from the topic.
Nevertheless, once we understand the different types of water, and see some helpful resources, making change becomes much easier.
So, let's dive in - pun intended : )
Today's Lesson: Water In The Laboratory
What you need to know and how to become sustainable
Number Of The Day
It takes approximately 0.33 kWh to condense 1 liter of water - as much energy as charging your phone 10-20 times. Important to consider, especially since distilled water is commonly used in laboratories, as we will discuss later. Remember, sustainability is interconnected: the more water we use, the more energy and resources are required too.
0.33
Handling Water Sustainably
While everyone is aware that electricity is a valuable good, water, probably due to its apparently natural origin does not receive as much attention. Espeially in regions that can source it abundantly.
Although data is very focused on the US, I found this graphic very intriguing. It stems from I2SL and EPA Water Sense “Best Practices Guide Water Efficiency in Laboratories”. They state a courtesy to Janice A. Beecher of the Institute of Public Utilities at Michigan State University.
As with plastics, where we have to differentiate different types, there are different types of water in terms of purity.
Although many scientists are aware that different purity grades exist, few understand what they mean or which exact water is required for specific processes.
Almost Like School: Grades I, II, and III
Although various grading systems exist, and organizations may set their own reference values, laboratory water is commonly categorized into three primary grades:
Grade I (Ultrapure Water)
This is the highest purity water used in labs. It is primarily used in sensitive applications such as high-performance liquid chromatography (HPLC), molecular biology, and atomic absorption spectrophotometry.
Grade II (Pure Water)
This is water of intermediate purity, suitable for less demanding applications like media preparation, buffer solutions, and general laboratory reagents.
Grade III (General Laboratory Water)
This is the lowest purity water, primarily used for non-critical applications like glassware rinsing, heating baths, and autoclave operations.
The data for this graph stems from I2SL and EPA Water Sense “Best Practices Guide Water Efficiency in Laboratories”. They state this is typical EPA laboratory building water use, based on data collected during water assessments conducted at EPA’s laboratories between 2011 and 2019. Note that Make-Up Water is basically the water going into the water tower.
What About The dd?
In addition, there are single-distilled water (dH₂O) and double-distilled water (ddH₂O), which typically fall within Grades II-III.
Deionized water (DI water), is purified by removing ions through ion-exchange processes rather than distillation. It is often used interchangeably with distilled water, although it may retain organic impurities that distillation removes.
You will also encounter other kinds of water like nuclease-free water for PCRs. One option to make water nuclease-free, it is treated with diethylpyrocarbonate (DEPC) and/or autoclaved to inactivate nucleases. However, DEPC can be toxic, so treated water must be thoroughly autoclaved to remove any remaining DEPC.
How is Purity Measured?
Let us briefly address the most important measures, but others, such as pH and silica content, may be measured too, depending on the application.
Conductivity & Resistivity: Measure the ionic content of water. For Grade I water, resistivity should be ≥ 18 MΩ·cm, and conductivity ≤ 0.055 μS/cm.
Absorbance at 254 nm: Indicates the presence of organic compounds.
Oxidizable Matter: Measures organic or inorganic compounds, particularly those that interfere with oxygen-sensitive reactions.
How is Water Purified?
Again, there are several methods, but these are the most common, (they are often combined to create high-purity water):
Advantages: Removes 90-99% of dissolved solids, bacteria, and pyrogens with low energy consumption compared to distillation.
Disadvantages: Membranes can become fouled and require regular maintenance. Does not remove gases or some organic compounds.
UV Radiation
Advantages: Kills bacteria, viruses, and other microorganisms without adding chemicals. Fast and low maintenance. Disadvantages: Does not remove dissolved salts, heavy metals, or particulates. Effectiveness decreases if the water is cloudy or turbid.
Microfiltration
Advantages: Removes particulate matter and bacteria. Simple and relatively low-cost.
Disadvantages: Does not remove dissolved salts or organic compounds.
Ultrapure Water – A Hidden Water Drain
Depending on the purification method, it can take up to 5 liters of tap water to produce 1 liter of ultrapure water!
Yes, although the environmental impact of water use varies a lot by location, reducing energy consumption will certainly lower overall environmental impacts.
Applying The Knowledge
A) Optimize Water Usage
Use the appropriate grade of water for each application. For non-critical tasks like rinsing, use lower-grade water (Grade III), and reserve higher-grade water for later wash cycles. Use soaking to avoid unnecessary use of water. Also, reduce the amount of ice is you take to cool tubes and plates to save both energy and water.
B) Low-Flow Aerators
Many lab faucets can run at rates as high as 4 gallons per minute, which is excessive for most lab activities. Installing low-flow aerators can reduce water usage dramatically. A case study by My Green Lab at the University of California, San Diego, showed that installing aerators reduced water usage by 300,000 to 900,000 gallons per year.
C) Monitoring Water Quality Regularly
If you can get in touch with administration, unnecessary over-filtration or purification by regularly monitoring water quality and adjusting purification systems to the specific needs of the experiment.
D) Reusing "Wastewater"
Reassess whether water used in one process can be reused for another. With some expertise, systems can be implemented to recycle reject water from reverse osmosis processes, reducing water waste.
This is the counter-current rinsing principle. The goal is to have the cleanest water is used last. This picture comes from the New Mexico Office of the State Engineer 1999. In the Labs 21st Century Water Efficiency Guide you can read more.
E) Water Using Equipment
Water aspirators and traditional condensers often waste large amounts of water in a short time. Replacing them with mechanical or electric vacuum pumps and using waterless condensers can save significant amounts of water.
Waterless Condensers simply use a specific galss forming technique during manufacturing in order to increase surface.
F) Single-Pass Cooling Systems
Single-pass (once-through) cooling is one of the largest water wasters in laboratories. Installing recirculating cooling systems, which reuse water in a closed loop, is highly recommended. If this isn't feasible, use the minimum flow rate necessary for cooling or install automatic control systems that allow water to flow only when the equipment is operating.
G) Looking for Innovations
One example that was impressive to me: there are many benchtop water sterilization options available. Nowadays, even a few models with exchangeable cartridges use a matrix to purify water, which can be reused after laboratory use, offering a more sustainable option compared to throwing away the entire cartridge.
There are some more topics that we have not covered, for example:
Reverse Osmosis Systems | Batch-type vs Tunnel Washers | Animal Water Supply | Wet scrubbers | Wash Down In Hoods | Water Use In Cooling Towers | HVAC Condensation Water
More about those topics and how to map water consumption for more efficient design, you can find right here or here.
Upcoming Lesson:
Who Invented the "Carbon Footprint"
Asking You
To cool down a sterilizer, it takes how much water each minute?
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